The present invention provides novel radiopharmaceuticals useful for imaging the heart, brain, lungs, liver or kidneys, kits useful for preparing the radiopharmaceuticals, and methods of imaging the heart, brain, lungs, liver or kidneys in a patient in need of such imaging.
Radiopharmaceuticals form the chemical basis for the medical specialty of nuclear medicine, a group of techniques used for diagnosis and therapy of a variety of diseases. In vivo diagnostic information is obtained by intravenous injection of the radiopharmaceutical and determining its biological distribution using a gamma camera. The distribution usually takes a form that is organ or lesion specific. From the distribution of the radiopharmaceutical and its behavior over time, it is possible to obtain information about the presence, progression and state of a disease.
Radiopharmaceuticals useful for imaging the heart based on homoleptic Tc-99m-isonitrile complexes have been described by Jones et. al. in U.S. Pat. No. 4,452,774 and Bergstein et. al. in U.S. Pat. No. 4,988,827. Radiopharmaceuticals based on technetium-99m complexes of binary ligand systems have been described by Bergstein et. al. in U.S. Pat. No. 5,279,811 for imaging the brain, Kelly et. al. in U.S. Pat. No. 5,045,302 for imaging the heart, Nosco in U.S. Pat. No. 5,330,738 for imaging the kidneys, as well as others. A recent review of radiopharmaceuticals based on metal radionuclide complexes is provided by Jurisson et. al., Chem. Rev. 1993, 93, 1137.
The biological properties of metal radionuclide complexes are determined by their chemical and physical properties, such as lipophilicity and charge, as opposed to conjugates of a metal radionuclide complex and a biologically active molecule in which the biological properties of the conjugate are determined by the biologically active molecule. The chemical and physical properties of the complexes are determined by the ligand system used and the choice of the substituents on the ligand or ligands. Therefore, for any particular ligand system, the choice of substituents will control the biological properties of the complex and the ultimate utility as a radiopharmaceutical. An example of this effect is the fact that the Tc-99m complex of N,Nxe2x80x2-1,2-ethylenediyl-bis-L-cysteine diethyl ester (ECD) is a brain imaging agent while the Tc-99m complex of N,Nxe2x80x2-1,2-ethylenediyl-bis-L-cysteine (EC), in which the two ester groups are replaced by carboxylic acid groups, is a renal imaging agent.
For metal radionuclide complexes with a homoleptic ligand system, such as the Tc-99m-isonitriles, Tc(CNR)6+, a change in the substituent, R, is replicated six times, making it difficult to precisely control the chemical and physical properties of the complexes. For complexes comprised of a binary ligand system the substituents can be independently changed on the two types of ligands, giving somewhat better control. Superior control of the properties should be achievable for complexes comprised of a ternary ligand system in which the substituents on the three types of ligands can be independently varied. However, as the order of the ligand system increases the probability of forming complexes of one single stoichiometry is expected to decrease.
Archer et. al., European Patent Application 90914225.9 describes a series of technetium-99m complexes having a ternary ligand system comprised of a hydrazido or diazenido ligand, a phosphine ligand and a halide, in which the substituents on the hydrazido or diazenido ligand and those on the phosphine ligand can be independently varied; the halide ligand has no substituents. This disclosure does not teach or suggest how to achieve the superior control of biological properties that would result from a ternary ligand system in which the substituents on the three types of ligands can be independently varied.
Another important consideration for any radiopharmaceutical is specific activity, the amount of the radiopharmaceutical present in a dosage to the amount of unlabeled excess ligand or ligands used to synthesize the radiopharmaceutical. High specific activity is required when one or more of the ligands are either potentially toxic, very expensive to manufacture, or may compete with the radiopharmaceutical for a binding site in vivo, to minimize the amount of excess ligand in the dosage administered. The radiopharmaceuticals described by Archer et. al. are formed in low specific activity. Therefore, there remains a need for new radiopharmaceuticals comprised of a ternary ligand system for which the substituents on all three ligands can be independently varied and that can be formed in high specific activity.
The present invention provides novel radiopharmaceuticals useful for imaging the heart, brain, lungs, liver or kidneys, kits useful for preparing the radiopharmaceuticals, and methods of imaging the heart, brain, lungs, liver or kidneys in a patient in need of such imaging. The radiopharmaceuticals are comprised of technetium or rhenium radionuclide complexes of a ternary ligand system: one hydrazido or diazenido ligand, one aminoalcohol ligand, and one pi-acid ligand selected from phosphines, arsines, and imine nitrogen-containing heterocycles. The radiopharmaceuticals can be formed in high specific activity, are stable in vitro, and their biological properties can be tailored by the selection of substituents on the three ligands.
[1] In a first embodiment, the present invention provides a novel radiopharmaceutical of the formula:
xe2x80x83ML1L2L3
or a pharmaceutically acceptable salt thereof, wherein,
M is 99mTc, 186Re or 188Re;
L1 is a ligand having the formula xe2x95x90Nxe2x80x94NR1R2 or xe2x95x90N+xe2x95x90NR1;
R1 is selected from the group: aryl substituted with 0-3 R3, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3, C1-C10 alkyl substituted with 0-3 R3, and C3-13 cycloalkyl substituted with 0-3 R3;
R2 is selected from the group: hydrogen, aryl substituted with 0-3 R3, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3, C1-C10 alkyl substituted with 0-3 R3, and C3-13 cycloalkyl substituted with 0-3 R3;
R3 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R4, xe2x80x94C(xe2x95x90O)R4, xe2x80x94C(xe2x95x90O)N(R4)2, xe2x80x94CH2OR4, xe2x80x94OC(xe2x95x90O)R4, xe2x80x94OC(xe2x95x90O)OR4, xe2x80x94OR4, xe2x80x94OC(xe2x95x90O)N(R4)2, xe2x80x94NR4C(xe2x95x90O)R4, xe2x80x94NR4C(xe2x95x90O)OR4, xe2x80x94NR4C(xe2x95x90O)N(R4)2, xe2x80x94NR4SO2N(R4)2, xe2x80x94NR4SO2R4, xe2x80x94SO3H, xe2x80x94SO2R4, xe2x80x94S(xe2x95x90O)R4, xe2x80x94SO2N(R4)2, xe2x80x94N(R4)2, xe2x80x94N(R4)3+, xe2x80x94NHC(xe2x95x90NH)NHR4, xe2x80x94C(xe2x95x90NH)NHR4, xe2x95x90NOR4, xe2x80x94NO2, xe2x80x94C(xe2x95x90O)NHOR4, xe2x80x94C(xe2x95x90O)NHN(R4)2, xe2x80x94OCH2CO2H, 2-(1-morpholino)ethoxy, C1-C10 alkyl substituted with 0-3 R5, C2-C10 alkenyl substituted with 0-3 R5, C3-C6 cycloalkyl substituted with 0-3 R5, aryl substituted with 0-3 R5, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R5;
R4 is independently selected at each occurrence from the group: H, C1-C10 alkyl substituted with 0-3 R5, C2-C10 alkenyl substituted with 0-3 R5, C3-C6 cycloalkyl substituted with 0-3 R5, aryl substituted with 0-3 R5, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R5;
R5 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R6, xe2x80x94C(xe2x95x90O)R6, xe2x80x94C(xe2x95x90O)N(R6)2, xe2x80x94CH2OR6, xe2x80x94OC(xe2x95x90O)R6, xe2x80x94OC(xe2x95x90O)OR6, xe2x80x94OR6, xe2x80x94OC(xe2x95x90O)N(R6)2, xe2x80x94NR6C(xe2x95x90O)R6, xe2x80x94NR6C(xe2x95x90O)OR6, xe2x80x94NR6C(xe2x95x90O)N(R6)2, xe2x80x94NR6SO2N(R6)2, xe2x80x94NR6SO2R6, xe2x80x94SO3H, xe2x80x94SO2R6, xe2x80x94S(xe2x95x90O)R6, xe2x80x94SO2N(R6)2, xe2x80x94N(R6)2, xe2x80x94N(R6)3+, xe2x80x94NHC(xe2x95x90NH)NHR6, xe2x80x94C(xe2x95x90NH)NHR6, xe2x95x90NOR6, xe2x80x94NO2, xe2x80x94C(xe2x95x90O)NHOR6, xe2x80x94C(xe2x95x90O)NHNR6R6, xe2x80x94OCH2CO2H, and phenyl;
provided that when R1 is pyridyl-R3, R3 is C(O)N(R4)2, and one R4 is alkyl-(R5)2, then R5 at each occurrence is other than phenyl;
R6 is independently selected at each occurrence from the group: H, and C1-C6 alkyl;
L2 is a ligand having the formula
(R11)(R12)(R13)Cxe2x80x94N(R7)xe2x80x94(C(R8) (R9))mxe2x80x94R10
R7 is selected from the group: hydrogen, hydroxy, aryl substituted with 0-3 R14, and C1-C10 alkyl substituted with 0-3 R15;
alternatively, R7 and R8 together form a 3-6 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14;
R8 and R9 are independently selected from the group: hydrogen, hydroxyl, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14, C1-C10 alkyl substituted with 0-3 R15, and C3-13 cycloalkyl substituted with 0-3 R15;
alternatively, R8 and R9 can be taken together to form a C3-C6 cycloalkyl substituted with 0-3 R15;
R10 is selected from the group: xe2x80x94COOH, phenyl substituted with 0-3 R14, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14;
R11 and R12 are independently selected at each occurrence from the group: H, xe2x80x94OH, xe2x80x94COOH, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14, C1-C10 alkyl substituted with 0-3 R15, and C3-13 cycloalkyl substituted with 0-3 R15;
alternatively, R7 and R11 together form a 3-6 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14;
R13 is xe2x80x94CH2OH, or xe2x80x94CH2CH2OH;
m is 0-2;
R14 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R15, C2-C5 alkenyl substituted with 0-3 R15, C3-C6 cycloalkyl substituted with 0-3 R15, aryl substituted with 0-3 R15, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R15, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OC(xe2x95x90O)OR16, xe2x80x94OR16, xe2x80x94OC(xe2x95x90O)N(R16)2, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16C(xe2x95x90O)OR16, xe2x80x94NR16C(xe2x95x90O)N(R16)2, xe2x80x94NR16SO2N(R16)2, xe2x80x94NR16SO2Rl6, xe2x80x94SO3H, xe2x80x94SO2R16, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR16, xe2x80x94C(xe2x95x90NH)NHR16, NO2, xe2x80x94OCH2CO2H;
R15 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OC(xe2x95x90O)OR16, xe2x80x94OR16, xe2x80x94OC(xe2x95x90O)N(R16)2, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16C(xe2x95x90O)OR16, xe2x80x94NR16C(xe2x95x90O)N(R16)2, xe2x80x94NR16SO2N(R16)2, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2R16, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR16, xe2x80x94C(xe2x95x90NH)NHR16, NO2, and xe2x80x94OCH2CO2H;
R16 is independently selected at each occurrence from the group: hydrogen, and C1-C6 alkyl;
L3 is a ligand having a formula selected from the group: 
A1 is selected from the group: PR17R18R19 and AsR17R18R19;
A2 and A3 are independently selected at each occurrence from the group: PR17R18 and AsR17R18;
R17, R18, and R19 are independently selected at each occurrence from the group: aryl substituted with 0-3 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R20, aralkyl substituted with 0-3 R20, arylalkaryl substituted with 0-3 R20, C1-C10 alkyl substituted with 0-3 R21, and C3-13 cycloalkyl substituted with 0-3 R21;
W is a spacer group selected from the group: aryl substituted with 0-3 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R20, aralkyl substituted with 0-3 R20, C1-C10 alkyl substituted with 0-3 R21, and C3-13 cycloalkyl substituted with 0-3 R21;
R20 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R21, C2-C5 alkenyl substituted with 0-3 R21, C3-C6 cycloalkyl substituted with 0-3 R21, aryl substituted with 0-3 R21, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R21, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94OC(xe2x95x90O)OR22, xe2x80x94OR22, xe2x80x94OC(xe2x95x90O)N(R22)2, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22C(xe2x95x90O)OR22, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, xe2x80x94NR22C(xe2x95x90O)N(R22)2, xe2x80x94NR22SO2N(R22)2, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2R22, xe2x80x94SO2N(R22)2, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR22, xe2x80x94C(xe2x95x90NH)NHR22, NO2, and xe2x80x94OCH2CO2H;
R21 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94OC(xe2x95x90O)OR22, xe2x80x94OR22, xe2x80x94OC(xe2x95x90O)N(R22)2, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22C(xe2x95x90O)OR22, xe2x80x94NR22C(xe2x95x90O)N(R22)2, xe2x80x94NR22SO2N(R22)2, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2R22, xe2x80x94S(xe2x95x90O)R22, xe2x80x94SO2N(R22)2, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR22, xe2x80x94C(xe2x95x90NH)NHR22, xe2x95x90NOR22, NO2, xe2x80x94C(xe2x95x90O)NHOR22, xe2x80x94C(xe2x95x90O)NHN(R22)2, xe2x80x94OCH2CO2H;
R22 is independently selected at each occurrence from the group: hydrogen and C1-C6 alkyl;
X1 is independently selected at each occurrence from the group: CR23 and N;
X2 is independently selected at each occurrence from the group: CR23, CR23R23, N, NR23, O and S;
X3 is independently selected at each occurrence from the group: C, CR23, and N;
provided the total number of heteroatoms, X1, X2, and X3 in each ring of the ligand, L3, is 1, 2, 3, or 4;
Y is selected from the group: BR23xe2x80x94, CR23, (Pxe2x95x90O), (Pxe2x95x90S);
n is 0 or 1;
a, b, c, d, e and f indicate the positions of optional double bonds, provided that one of e and f is a double bond;
R23 is independently selected at each occurrence from the group: H, C1-C10 alkyl substituted with 0-3 R24, C2-C10 alkenyl substituted with 0-3 R24, C2-C10 alkynyl substituted with 0-3 R24, aryl substituted with 0-3 R24, C1-C10 alkoxy substituted with 0-3 R24, C3-13 carbocycle substituted with 0-3 R24, and R24;
or, alternatively, two R23 may be taken together with the atom or atoms to which they are attached to form a fused aromatic substituted with 0-3 R24, C5-7 carbocyclic ring substituted with 0-3 R24 or 5-7 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S, and substituted with 0-3 R24;
R24 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CO2R25, xe2x80x94C(xe2x95x90O)R25, xe2x80x94C(xe2x95x90O)N(R25)2, xe2x80x94N(R25)3+xe2x80x94CH2OR25, xe2x80x94OC(xe2x95x90O)R25, xe2x80x94OC(xe2x95x90O)OR25, xe2x80x94OR25, xe2x80x94OC(xe2x95x90O)N(R25)2, xe2x80x94NR25C(xe2x95x90O)R25, xe2x80x94NR25C(xe2x95x90O)OR25, xe2x80x94NR25C(xe2x95x90O)N(R25)2, xe2x80x94NR25SO2N(R25)2, xe2x80x94NR25SO2R25, xe2x80x94SO3H, xe2x80x94SO2R25, xe2x80x94SO2N(R25)2, xe2x80x94N(R25)2, xe2x80x94OCH2CO2H; and
R25 is independently selected at each occurrence from the group: hydrogen and C1-C6 alkyl.
[2] In a preferred embodiment, the present invention provides novel radiopharmaceuticals, wherein:
M is 99mTc;
R1 is selected from the group: aryl substituted with 0-3 R3, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3;
R2 is selected from the group: hydrogen, aryl substituted with 0-3 R3, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3;
R3 is independently selected at each occurrence from the group: F, Cl, Br, I, xe2x80x94CO2R4, xe2x80x94C(xe2x95x90O)N(R4)2, xe2x80x94CH2OR4, xe2x80x94OC(xe2x95x90O)R4, xe2x80x94OR4, xe2x80x94NR4C(xe2x95x90O)R4, xe2x80x94NR4SO2R4, xe2x80x94SO3H, xe2x80x94SO2N(R4)2, xe2x80x94N(R4)2, xe2x80x94N(R4)3+, xe2x80x94NO2, xe2x80x94OCH2CO2H, and C1-C10 alkyl substituted with 0-3 R5;
R4 is independently selected at each occurrence from the group: H, and C1-C10 alkyl substituted with 0-3 R5;
R5 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CO2R6, xe2x80x94C(xe2x95x90O)N(R6)2, xe2x80x94CH2OR6, xe2x80x94OC(xe2x95x90O)R6, xe2x80x94OR6, xe2x80x94NR6C(xe2x95x90O)R6, xe2x80x94NR6SO2R6, xe2x80x94SO3H, xe2x80x94SO2N(R6)2, xe2x80x94N(R6)2, xe2x80x94N(R6)3+, xe2x80x94NO2, xe2x80x94OCH2CO2H, and phenyl;
R7 is selected from the group: hydrogen, and C1-C10 alkyl substituted with 0-3 R15;
R8 and R9 are independently selected from the group: hydrogen, hydroxyl, and C1-C10 alkyl substituted with 0-3 R15;
R11 and R12 are independently selected at each occurrence from the group: H, xe2x80x94OH, and C1-C10 alkyl substituted with 0-3 R15;
m is 0-1;
R14 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R15, F, Cl, Br, I, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OR16, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, xe2x80x94NO2, and xe2x80x94OCH2CO2H;
R15 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OR16, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, and xe2x80x94OCH2CO2H;
L3 is a ligand having a formula selected from the group: 
A1 is PR17R18R19;
R17, R18, and R19 are independently selected from the group: aryl substituted with 0-3 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R20, and C1-C10 alkyl substituted with 0-3 R21;
R20 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R21, F, Cl, Br, I, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94OR22, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2N(R22)2, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, xe2x80x94PO3H2, and xe2x80x94OCH2CO2H;
R21 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94PO3H2, xe2x80x94OR22, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2N(R22)2, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, and xe2x80x94OCH2CO2H;
x2 is independently selected at each occurrence from the group: CR23, CR23R23, N, NR23, and O;
provided the total number of heteroatoms, X1 and X2, is 1, 2, 3, or 4;
R23 is independently selected at each occurrence from the group: H, C1-C3 alkyl substituted with 0-3 R24, aryl substituted with 0-3 R24, and R24;
alternatively, two R23""s may be taken together with the atom or atoms to which they are attached to form a fused aromatic substituted with 0-3 R24 or a 5-7 membered heterocyclic ring containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R24; and,
R24 is independently selected at each occurrence from the group: xe2x80x94NO2, xe2x80x94CO2R25, xe2x80x94OR25, xe2x80x94SO3H, and xe2x80x94OCH2CO2H.
[3] In a further preferred embodiment, the present invention provides novel radiopharmaceuticals, wherein:
R1 is selected from the group: aryl substituted with 0-1 R3, and heterocycle substituted with 0-1 R3, wherein said heterocycle is pyridine or phthalazine;
R2 is selected from the group: hydrogen, and aryl substituted with 0-1 R3;
R3 is independently selected at each occurrence from the group: Cl, xe2x80x94CO2R4, xe2x80x94C(xe2x95x90O)N(R4)2, xe2x80x94OR4, xe2x80x94SO3H, and xe2x80x94NO2;
R4 is independently selected at each occurrence from the group: H, and C1-C10 alkyl substituted with 0-2 R5;
R5 is selected from the group: xe2x80x94CO2R6, xe2x80x94OR6, and phenyl;
R6 is independently selected from the group: H and methyl;
R7, R8, and R9 are each hydrogen;
R10 is selected from the group: xe2x80x94COOH, and 2-hydroxyphenyl;
m is 0-1,
provided that when R10 is xe2x80x94COOH, m is 1;
R11, R12, and R13 are each xe2x80x94CH2OH;
A1 is PR17R18R19;
R17, R18and R19 are independently selected from the group: aryl substituted with 0-1 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-1 R20, and C1-C3 alkyl substituted with 0-1 R21;
R20 is independently selected at each occurrence from the group: xe2x80x94CO2R22, xe2x80x94OR22, and xe2x80x94SO3H;
R21 is selected from the group: xe2x80x94CO2R22, and xe2x80x94OR22;
R22 is independently selected from the group: H, and methyl;
X1 is CH; and,
X2 is independently selected at each occurrence from the group: CH, and NH, provided only one X2 is NH.
[4] In an even further prei-erred embodiment, the radiopharmaceutical is selected from the group:
[99mTc(HYPY) (tricine) (TPPTS)];
[99mTc(HYPY) (tricine) (TPPMS)];
[99mTc(HYPY) (tricine) (imidazole)];
[99mTc(HYPY) (tricine) (pyridine)];
[99mTc(HYPY) (tricine) (TFP)];
[99mTc(HYPY) (tricine) (PPh3)];
[99mTc(HYNICamide) (tricine) (TPPTS)];
[99mTc(HYNIC-DMA) (tricine) (TPPTS)];
[99mTc(HYNIC-Gly-OMe) (tricine) (TPPTS)];
[99mTc(HYNIC-D-Phe-OMe)(tricine)(TPPTS)];
[99mTc(DPH) (tricine) (TPPTS)];
[99mTc(DPH) (tricine) (TFP)];
[99mTc(DPH) (tricine) (TPPMS)];
[99mTc(DPH) (tricine) (PPh3)];
[99mTc(11-(6-hydrazinonicotinamido)undecanoic acid)(tricine)(TPPTS)];
[99mTc(11-(6-hydrazinonicotinamido)undecanoic acid)(tricine)(imidazole)];
[99mTc(11-(6-hydrazinonicotinamido)undecanoic acid)(tricine)(pyridine)];
[99mTc(11-(6-hydrazinonicotinamido)undecanoic acid)(tricine)(TFP)];
[99mTc(PHY) (tricine) (TPPTS)];
[99mTc(HYLA) (tricine) (TPPTS)];
[99mTc(4-Cl-PHY) (tricine) (TPPTS)];
[99mTc(HYPY) (hbtris) (TPPTS)];
[99mTc(HYLA) (hbtris) (TPPTS)];
[99mTc(4-Cl-PHY) (hbtris) (TPPTS)]; and,
[99mTc(4-NO2-PHY) (hbtris) (TPPTS)].
[5] In a second embodiment, the present invention provides a novel kit for preparing a radiopharmaceutical, comprising:
(a) a pharmaceutically acceptable first ligand having the formula R1R2Nxe2x80x94NH2 or a ligand precursor having the formula R1R2Nxe2x80x94Nxe2x95x90CR26R27;
(b) a pharmaceutically acceptable second ligand having the formula:
(R11)(R12)(R13)Cxe2x80x94N(R7)xe2x80x94(C(R8)(R9))mxe2x80x94R10;
and,
(c) a pharmaceutically acceptable third ligand having a formula selected from the group: 
R1 is selected from the group: aryl substituted with 0-3 R3, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3, C1-C10 alkyl substituted with 0-3 R3, and cycloalkyl substituted with 0-3 R3;
R2 is selected from the group: hydrogen, aryl substituted with 0-3 R3, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3, C1-C10 alkyl substituted with 0-3 R3, and cycloalkyl substituted with 0-3 R3;
R3 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R4, xe2x80x94C(xe2x95x90O)R4, xe2x80x94C(xe2x95x90O)N(R4)2, xe2x80x94CH2OR4, xe2x80x94OC(xe2x95x90O)R4, xe2x80x94OC(xe2x95x90O)OR4, xe2x80x94OR4, xe2x80x94OC(xe2x95x90O)N(R4)2, xe2x80x94NR4C(xe2x95x90O)R4, xe2x80x94NR4C(xe2x95x90O)OR4, xe2x80x94NR4C(xe2x95x90O)N(R4)2, xe2x80x94NR4SO2N(R4)2, xe2x80x94NR4SO2R4, xe2x80x94SO3H, xe2x80x94SO2R4, xe2x80x94S(xe2x95x90O)R4, xe2x80x94SO2N(R4)2, xe2x80x94N(R4)2, xe2x80x94N(R4)3+, xe2x80x94NHC(xe2x95x90NH)NHR4, xe2x80x94C(xe2x95x90NH)NHR4, xe2x95x90NOR4, xe2x80x94NO2, xe2x80x94C(xe2x95x90O)NHOR4, xe2x80x94C(xe2x95x90O)NHN(R4)2, xe2x80x94OCH2C2H, 2-(1-morpholino)ethoxy, C1-C10 alkyl substituted with 0-3 R5, C2-C10 alkenyl substituted with 0-3 R5, C3-C6 cycloalkyl substituted with 0-3 R5, aryl substituted with 0-3 R5, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R5;
R4 is independently selected at each occurrence from the group: H, C1-C10 alkyl substituted with 0-3 R5, C2-C10 alkenyl substituted with 0-3 R5, C3-C6 cycloalkyl substituted with 0-3 R5, aryl substituted with 0-3 R5, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R5; p2 R5 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R6, xe2x80x94C(xe2x95x90O)R6, xe2x80x94C(xe2x95x90O)N(R6)2, xe2x80x94CH2OR6, xe2x80x94OC(xe2x95x90O)R6, xe2x80x94OC(xe2x95x90O)OR6, xe2x80x94OR6, xe2x80x94OC(xe2x95x90O)N(R6)2, xe2x80x94NR6C(xe2x95x90O)R6, xe2x80x94NR6C(xe2x95x90O)OR6, xe2x80x94NR6C(xe2x95x90O)N(R6)2, xe2x80x94NR6SO2N(R6)2, xe2x80x94NR6SO2R6, xe2x80x94SO3H, xe2x80x94SO2R6, xe2x80x94S(xe2x95x90O)R6, xe2x80x94SO2N(R6)2, xe2x80x94N(R6)2, xe2x80x94N(R6)3+, xe2x80x94NHC(xe2x95x90NH)NHR6, xe2x80x94C(xe2x95x90NH)NHR6, xe2x95x90NOR6, xe2x80x94NO2, xe2x80x94C(xe2x95x90O)NHOR6, xe2x80x94C(xe2x95x90O)NHNR6R6, xe2x80x94OCH2C2H, and phenyl;
provided that when R1 is pyridyl-R3, R3 is C(O)N(R4)2, and one R4 is alkyl-(R5)2, then R5 at each occurrence is other than phenyl;
R6 is independently selected at each occurrence from the group: H, and C1-C6 alkyl;
R7 is selected from the group: hydrogen, hydroxy, aryl substituted with 0-3 R14, and C1-C10 alkyl substituted with 0-3 R15;
alternatively, R7 and R8 together form a 3-6 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14;
R8 and R9 are independently selected from the group: hydrogen, hydroxyl, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14, C1-C10 alkyl substituted with 0-3 R15, and cycloalkyl substituted with 0-3 R15;
alternatively, R8 and R9 can be taken together to form a C3-C6 cycloalkyl substituted with 0-3 R15;
R10 is selected from the group: xe2x80x94COOH, phenyl substituted with 0-3 R14, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14;
R11 and R12 are independently selected at each occurrence from the group: H, xe2x80x94OH, xe2x80x94COOH, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14, C1-C10 alkyl substituted with 0-3 R15, and cycloalkyl substituted with 0-3 R15;
alternatively, R7 and R11together form a 3-6 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R14 
R13 is xe2x80x94CH2OH, or xe2x80x94CH2CH2OH;
m is 0-2;
R14 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R15, C2-C5 alkenyl substituted with 0-3 R15, C3-C6 cycloalkyl substituted with 0-3 R15, aryl substituted with 0-3 R15, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R15, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OC(xe2x95x90O)OR16, xe2x80x94OR16, xe2x80x94OC(xe2x95x90O)N(R16)2, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16C(xe2x95x90O)OR16, xe2x80x94NR16C(xe2x95x90O)N(R16)2, xe2x80x94NR16SO2N(R16)2, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2R16, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR16, xe2x80x94C(xe2x95x90NH)NHR16, NO2, xe2x80x94OCH2CO2H;
R15 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OC(xe2x95x90O)OR16, xe2x80x94OR16, xe2x80x94OC(xe2x95x90O)N(R16)2, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16C(xe2x95x90O)OR16, xe2x80x94NR16C(xe2x95x90O)N(R16)2, xe2x80x94NR16SO2N(R16)2, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2R16, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR16, xe2x80x94C(xe2x95x90NH)NHR16, NO2, and xe2x80x94OCH2CO2H;
R16 is independently selected at each occurrence from the group: hydrogen, and C1-C6 alkyl;
A1 is selected from the group: PR17R18R19 and AsR17R18R19;
A2 and A3 are independently selected at each occurrence from the group: PR17R18 and AsR17R18;
R17,R18, and R19 are independently selected at each occurrence from the group: aryl substituted with 0-3 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R20, aralkyl substituted with 0-3 R20, arylalkaryl substituted with 0-3 R20, C1-C10 alkyl substituted with 0-3 R21, and cycloalkyl substituted with 0-3 R21;
W is a spacer group selected from the group: aryl substituted with 0-3 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R20, aralkyl substituted with 0-3 R20, C1-C10 alkyl substituted with 0-3 R21, and cycloalkyl substituted with 0-3 R21;
R20 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R21, C2-C5 alkenyl substituted with 0-3 R21, C3-C6 cycloalkyl substituted with 0-3 R21, aryl substituted with 0-3 R21, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R21, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94OC(xe2x95x90O)OR22, xe2x80x94OR22, xe2x80x94OC(xe2x95x90O)N(R22)2, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22C(xe2x95x90O)OR22, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, xe2x80x94NR22C(xe2x95x90O)N(R22)2, xe2x80x94NR22SO2N(R22)2, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2R22, xe2x80x94SO2N(R22)2, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR22, xe2x80x94C(xe2x95x90NH)NHR22, NO2, and xe2x80x94OCH2CO2H;
R21 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94OC(xe2x95x90O)OR22, xe2x80x94OR22, xe2x80x94OC(xe2x95x90O)N(R22)2, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22C(xe2x95x90O)OR22, xe2x80x94NR22C(xe2x95x90O)N(R22)2, xe2x80x94NR22SO2N(R22)2, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2R22, xe2x80x94S(xe2x95x90O)R22, xe2x80x94SO2N(R22)2, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, xe2x80x94PO3H2, xe2x80x94NHC(xe2x95x90NH)NHR22, xe2x80x94C(xe2x95x90NH)NHR22, xe2x95x90NOR22, NO2, xe2x80x94C(xe2x95x90O)NHOR22, xe2x80x94C(xe2x95x90O)NHN(R22)2, xe2x80x94OCH2CO2H;
R22 is independently selected at each occurrence from the group: hydrogen and C1-C6 alkyl;
X1 is independently selected at each occurrence from the group: CR23 and N;
X2 is independently selected at each occurrence from the group: CR23, CR23R23, N, NR23, O and S;
X3 is independently selected at each occurrence from the group: C, CR23, and N;
provided the total number of heteroatoms, X1, X2, and X3 in each ring of the ligand, L3, is 1, 2, 3, or 4;
Y is selected from the group: BR23-, CR23, (Pxe2x95x90O), (Pxe2x95x90S);
n is 0 or 1;
a, b, c, d, e and f indicate the positions of optional double bonds, provided that one of e and f is a double bond;
R23 is independently selected at each occurrence from the group: H, C1-C10 alkyl substituted with 0-3 R24, C2-C10 alkenyl substituted with 0-3 R24, C2-C10 alkynyl substituted with 0-3 R24, aryl substituted with 0-3 R24, C1-C10 alkoxy substituted with 0-3 R24, C3-13 carbocycle substituted with 0-3 R24, and R24;
alternatively, two R23 may be taken together with the atom or atoms to which they are attached to form a fused aromatic substituted with 0-3 R24, C5-7 carbocyclic ring substituted with 0-3 R24 or 5-7 membered heterocyclic ring containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R24;
R24 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CO2R25, xe2x80x94C(xe2x95x90O)R25, xe2x80x94C(xe2x95x90O)N(R25)2, xe2x80x94N(R25)3+, xe2x80x94CH2OR25, xe2x80x94OC(xe2x95x90O)R25, xe2x80x94OC(xe2x95x90O)OR25, xe2x80x94OR25, xe2x80x94OC(xe2x95x90O)N(R25)2, xe2x80x94NR25C(xe2x95x90O)R25, xe2x80x94NR25C(xe2x95x90O)OR25, xe2x80x94NR25C(xe2x95x90O)N(R25)2, xe2x80x94NR25SO2N(R25)2, xe2x80x94NR25SO2R25, xe2x80x94SO3H, xe2x80x94SO2R25, xe2x80x94SO2N(R25)2, xe2x80x94N(R25)2, xe2x80x94OCH2CO2H; and
R25 is independently selected at each occurrence from the group: hydrogen and C1-C6 alkyl;
R26 and R27 are independently selected from the group: H; C1-C10alkyl; xe2x80x94CN; xe2x80x94CO2R31; xe2x80x94C(xe2x95x90O)R31; xe2x80x94C(xe2x95x90O)N(R31)2; C2-C10 1-alkene substituted with 0-3 R30; C2-C10 1-alkyne substituted with 0-3 R30; aryl substituted with 0-3 R30; unsaturated 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R30; and unsaturated C3-13 carbocycle substituted with 0-3 R30;
alternatively, R26 and R27, may be taken together with the divalent carbon radical to which they are attached to form: 
R28 and R29 are independently selected at each occurrence from the group: H; R30; C1-C10 alkyl substituted with 0-3 R30; C2-C10 alkenyl substituted with 0-3 R30; C2-C10 alkynyl substituted with 0-3 R30; aryl substituted with 0-3 R30; 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R30; and C3-13 carbocycle substituted with 0-3 R30;
alternatively, R28 and R29 may be taken together to form a fused aromatic or 5-7 membered heterocyclic ring containing from 1-4 heteroatoms selected from N, O, and S;
g and h indicate the positions of optional double bonds and p is 0 or 1,
R30 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CF3, xe2x80x94CN, xe2x80x94CO2R31, xe2x80x94C(xe2x95x90O)R31, xe2x80x94C(xe2x95x90O)N(R31)2, xe2x80x94N(R31)3+, xe2x80x94CH2OR31, xe2x80x94OC(xe2x95x90O)R31, xe2x80x94OC(xe2x95x90O)OR31, xe2x80x94OR31, xe2x80x94OC(xe2x95x90O)N(R31)2, xe2x80x94NR31C(xe2x95x90O)R31, xe2x80x94NR31C(xe2x95x90O)OR31, xe2x80x94NR31C(xe2x95x90O)N(R31)2, xe2x80x94NR31SO2N(R31)2, xe2x80x94NR31SO2R31, xe2x80x94SO3H, xe2x80x94SO2R31, xe2x80x94SR31, xe2x80x94S(xe2x95x90O)R31, xe2x80x94SO2N(R31)2, xe2x80x94N(R31)2, xe2x80x94NHC(xe2x95x90NH)NHR31, xe2x80x94C(xe2x95x90NH)NHR31, xe2x95x90NOR31, xe2x80x94C(xe2x95x90O)NHOR31, xe2x80x94OCH2CO2H, 2-(1-morpholino)ethoxy; and
R31 is independently selected at each occurrence from the group: hydrogen, C1-C6 alkyl.
[6] In another preferred embodiment, the third ligand is selected from the group: 
R1 is selected from the group: aryl substituted with 0-3 R3, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3;
R2 is selected from the group: hydrogen, aryl substituted with 0-3 R3, and 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R3;
R3 is independently selected at each occurrence from the group: F, Cl, Br, I, xe2x80x94CO2R4, xe2x80x94C(xe2x95x90O)N(R4)2, xe2x80x94CH2OR4, xe2x80x94OC(xe2x95x90O)R4, xe2x80x94OR4, xe2x80x94NR4C(xe2x95x90O)R4, xe2x80x94NR4SO2R4, xe2x80x94SO3H, xe2x80x94SO2N(R4)2, xe2x80x94N(R4)2, xe2x80x94N(R4)3+, xe2x80x94NO2, xe2x80x94OCH2CO2H, and C1-C10 alkyl substituted with 0-3 R5;
R4 is independently selected at each occurrence from the group: H, and C1-C10 alkyl substituted with 0-3 R5;
R5 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CO2R6, xe2x80x94C(xe2x95x90O)N(R6)2, xe2x80x94CH2OR6, xe2x80x94OC(xe2x95x90O)R6, xe2x80x94OR6, xe2x80x94NR6C(xe2x95x90O)R6, xe2x80x94NR6SO2R6, xe2x80x94SO3H, xe2x80x94SO2N(R6)2, xe2x80x94N(R6)2, xe2x80x94N(R6)3+, xe2x80x94NO2, xe2x80x94OCH2CO2H, and phenyl;
R7 is selected from the group: hydrogen, and C1-C10 alkyl substituted with 0-3 R15;
R8 and R9 are independently selected from the group: hydrogen, hydroxyl, and C1-C10 alkyl substituted with 0-3 R15;
R11and R12 are independently selected at each occurrence from the group: H, xe2x80x94OH, and C1-C10 alkyl substituted with 0-3 R15;
m is 0-1;
R14 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R15, F, Cl, Br, I, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OR16, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, xe2x80x94NO2, and xe2x80x94OCH2CO2H;
R15 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CO2R16, xe2x80x94C(xe2x95x90O)N(R16)2, xe2x80x94CH2OR16, xe2x80x94OC(xe2x95x90O)R16, xe2x80x94OR16, xe2x80x94NR16C(xe2x95x90O)R16, xe2x80x94NR16SO2R16, xe2x80x94SO3H, xe2x80x94SO2N(R16)2, xe2x80x94PO3H2, and xe2x80x94OCH 22CO2H;
A1 is PR17R18R19;
R17, R18, and R19 are independently selected from the group: aryl substituted with 0-3 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R20, and C1-C10 alkyl substituted with 0-3 R21;
R20 is independently selected at each occurrence from the group: C1-C5 alkyl substituted with 0-3 R21, F, Cl, Br, I, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94OR22, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2N(R22)2, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, xe2x80x94PO3H2, and xe2x80x94OCH2CO2H;
R21 is independently selected at each occurrence from the group: xe2x95x90O, F, Cl, Br, I, xe2x80x94CO2R22, xe2x80x94C(xe2x95x90O)N(R22)2, xe2x80x94CH2OR22, xe2x80x94OC(xe2x95x90O)R22, xe2x80x94PO3H2, xe2x80x94OR22, xe2x80x94NR22C(xe2x95x90O)R22, xe2x80x94NR22SO2R22, xe2x80x94SO3H, xe2x80x94SO2N(R22)2, xe2x80x94N(R22)2, xe2x80x94N(R22)3+, and xe2x80x94OCH2CO2H;
X2 is independently selected at each occurrence from the group: CR23, CR23R23, N, NR23, and O;
provided the total number of heteroatoms, X1, and X2, is 1, 2, 3, or 4;
R23 is independently selected at each occurrence from the group: H, C1-C3 alkyl substituted with 0-3 R24, aryl substituted with 0-3 R24, and R24;
alternatively, two R23 may be taken together with the atom or atoms to which they are attached to form a fused aromatic or a 5-7 membered heterocyclic ring containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R24; and
R24 is independently selected at each occurrence from the group: xe2x80x94NO2, xe2x80x94CO2R25, xe2x80x94OR25, xe2x80x94SO3H, and xe2x80x94OCH2CO2H;
R26 and R27 are independently selected from the group: xe2x80x94CO2R31; C2-C5 1-alkene substituted with 0-3 R30; C2-C5 1-alkyne substituted with 0-3 R30; aryl substituted with 0-3 R30; and unsaturated 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-3 R30;
alternatively, R26 and R27, may be taken together with the divalent carbon radical to which they are attached to form: 
R28 and R29 may be independently selected from the group: H, and R30;
alternatively, R28, R29 may be taken together to form a fused aromatic or a 5-7 membered heterocyclic ring containing from 1-4 heteroatoms selected from N, O, and S;
g and h indicate the positions of optional double bonds and p is 0 or 1,
R30 is independently selected at each occurrence from the group: xe2x80x94CO2R31, xe2x80x94C(xe2x95x90O)N(R31)2, xe2x80x94CH2OR31, xe2x80x94OC(xe2x95x90O)R31, xe2x80x94OR34, xe2x80x94SO3H, xe2x80x94N(R34)2, and xe2x80x94OCH2CO2H; and,
R31 is independently selected at each occurrence from the group: hydrogen, and C1-C3 alkyl.
[7] In another even further preferred embodiment, the present invention provides novel kits wherein:
R1 is selected from the group: aryl substituted with 0-1 R3, and heterocycle substituted with 0-1 R3, wherein said heterocycle is pyridine or phthalazine;
R2 is selected from the group: hydrogen, and aryl substituted with 0-1 R3;
R3 is independently selected at each occurrence from the group: Cl, xe2x80x94CO2R4, xe2x80x94C(xe2x95x90O)N(R4)2, xe2x80x94OR4, xe2x80x94SO3H, and xe2x80x94NO2;
R4 is independently selected at each occurrence from the group: H, and C1-C10 alkyl substituted with 0-2 R5;
R5 is selected from the group: xe2x80x94CO2R6, xe2x80x94OR6, and phenyl;
R6 is independently selected from the group: H, and methyl;
R7, R8, and R9 are hydrogen;
R10 is selected from the group: xe2x80x94COOH, and 2-hydroxyphenyl;
m is 0-1,
provided that when R10 is xe2x80x94COOH, m is 1;
R11, R12, and R13 are xe2x80x94CH2OH;
A1 is PR17R18R19;
R17, R18, and R19 are independently selected from the group: aryl substituted with 0-1 R20, 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-1 R20, and C1-C3 alkyl substituted with 0-1 R21;
R20 is independently selected at each occurrence from the group: xe2x80x94CO2R22, xe2x80x94OR22, and xe2x80x94SO3H;
R21 is selected from the group: xe2x80x94CO2R22, and xe2x80x94OR22;
R22 is independently selected from the group: H, and methyl;
X1 is CH;
X2 is independently selected at each occurrence from the group: CH, and NH, provided only one X2 is NH;
R26 is selected from the group: xe2x80x94CO2R31; C2-C3 1-alkene substituted with 0-1 R30; aryl substituted with 0-1 R30; unsaturated 5-10 membered heterocycle containing from 1-4 heteroatoms selected from N, O, and S and substituted with 0-1 R30;
R27 is H;
R30 is independently selected at each occurrence from the group: xe2x80x94CO2R31, xe2x80x94OR31, xe2x80x94SO3H, and xe2x80x94N(R31)2; and
R31 is independently selected at each occurrence from the group: hydrogen, and methyl.
[8] In a still further preferred embodiment, the novel kit, further comprises: a reducing agent.
[9] In a more preferred embodiment, the reducing agent is Sn(II).
[10] In another still further preferred embodiment, the first ligand, the second ligand, and the third ligand are contained in the same vial.
Another embodiment of this invention is a method of imaging the heart in a mammal, comprising (i) administering an effective amount of one of the present radiopharmaceuticals and (ii) imaging said mammal using gamma scintigraphy.
Another embodiment of this invention is a method of imaging the brain in a mammal, comprising (i) administering an effective amount one of the present radiopharmaceuticals and (ii) imaging said mammal using gamma scintigraphy.
Another embodiment of this invention is a method of imaging the lungs in a mammal, comprising (i) administering an effective amount one of the present radiopharmaceuticals and (ii) imaging said mammal using gamma scintigraphy.
Another embodiment of this invention is a method of imaging the hepatobiliary system in a mammal, comprising (i) administering an effective amount of one of the present radiopharmaceuticals and (ii) imaging said mammal using gamma scintigraphy.
Another embodiment of this invention is a method of imaging the kidneys in a mammal, comprising (i) administering an effective amount of one of the present radiopharmaceuticals and (ii) imaging said mammal using gamma scintigraphy.
The following abbreviations are used herein:
HYPY=2-hydrazinopyridine,
HYNICamide=6-hydrazinonicotinamide,
HYNIC-DMA=6-hydrazino-N,N-dimethylnicotinamide,
HYNIC-Gly-OMe=6-hydrazinonicotinylglycine methyl ester,
HYNIC-D-Phe-OMe=6-hydrazinonicotinyl-D-phenylalanine methyl ester,
DPH=N,N-diphenylhydrazine,
PHY=phenylhydrazine,
HYLA=hydralazine,
4-Cl-PHY=4-chlorophenylhydrazine,
4-NO2-PHY=4-nitrophenylhydrazine,
hbtris=2-(2-hydroxybenzyl)amino-2-hydroxymethyl-1,3-propanediol,
TPPTS=tris(3-sulfonatophenyl)phosphine,
TPPMS=(3-sulfonatophenyl)diphenylphosphine, and
TFP=tris(2-furanyl)phosphine.
When any variable occurs more than one time in any constituent or in any formula, its definition on each occurrence is independent of its definition at every other occurrence. Thus, for example, if a group is shown to be substituted with 0-2 R52, then said group may optionally be substituted with up to two R52, and R52 at each occurrence is selected independently from the defined list of possible R52. Also, by way of example, for the group xe2x80x94N(R53)2, each of the two R53 substituents on N is independently selected from the defined list of possible R53. Combinations of substituents and/or variables are permissible only if such combinations result in stable compounds.
By xe2x80x9cstable compoundxe2x80x9d or xe2x80x9cstable structurexe2x80x9d is meant herein a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious diagnostic agent.
The term xe2x80x9csubstitutedxe2x80x9d, as used herein, means that one or more hydrogens on the designated atom or group is replaced with a selection from the indicated group, provided that the designated atom""s or group""s normal valency is not exceeded, and that the substitution results in a stable compound. When a substituent is keto (i.e., xe2x95x90O), then 2 hydrogens on the atom are replaced.
The term xe2x80x9cbondxe2x80x9d, as used herein, means either a single or double bond.
The term xe2x80x9csaltxe2x80x9d, as used herein, is used as defined in the CRC Handbook of Chemistry and Physics, 65th Edition, CRC Press, Boca Raton, Fla., 1984, as any substance which yields ions, other than hydrogen or hydroxyl ions.
As used herein, xe2x80x9calkylxe2x80x9d is intended to include both branched and straight-chain saturated aliphatic hydrocarbon groups having the specified number of carbon atoms, examples of which include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, and t-butyl; xe2x80x9ccycloalkylxe2x80x9d or xe2x80x9ccarbocyclexe2x80x9d is intended to include saturated and partially unsaturated ring groups, including any stable 3- to 10-membered monocyclic or 7-13-membered bi- or poly-cyclic ring system, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and adamantyl; xe2x80x9cbicycloalkylxe2x80x9d is intended to include saturated bicyclic ring groups such as [3.3.0]bicyclooctane, [4.3.0]bicyclononane, [4.4.0]bicyclodecane (decalin), and [2.2.2]bicyclooctane.
As used herein, the term xe2x80x9calkenexe2x80x9d or xe2x80x9calkenylxe2x80x9d is intended to include both branched and straight-chain groups of the formula CnH2n-1 having the specified number of carbon atoms, such as ethenyl and propenyl.
As used herein, the term xe2x80x9calkynexe2x80x9d or xe2x80x9calkynylxe2x80x9d is intended to include both branched and straight-chain groups of the formula CnH2nxe2x88x923 having the specified number of carbon atoms, such as ethynyl and propynyl.
As used herein, xe2x80x9carylxe2x80x9d or xe2x80x9caromatic residuexe2x80x9d is intended to mean phenyl or naphthyl, which when substituted, the substitution can be at any position.
As used herein, the term xe2x80x9cheterocyclexe2x80x9d or xe2x80x9cheterocyclic systemxe2x80x9d is intended to mean a stable 5- to 7-membered monocyclic or bicyclic or 7- to 10-membered bicyclic heterocyclic ring which is saturated partially unsaturated or unsaturated (aromatic), and which consists of carbon atoms and from 1, 2, 3, or 4 heteroatoms independently selected from the group consisting of N, O and S and including any bicyclic group in which any of the above-defined heterocyclic rings is fused to a benzene ring. The nitrogen and sulfur heteroatoms may optionally be oxidized. The heterocyclic ring may be attached to its nendant group at any heteroatom or carbon atom which results in a stable structure. The heterocyclic rings described herein may be substituted on carbon or on a nitrogen atom if the resulting compound is stable. If specifically noted, a nitrogen in the heterocycle may optionally be quaternized. It is preferred that when the total number of S and O atoms in the heterocycle exceeds 1, then these heteroatoms are not adjacent to one another. It is preferred that the total number of S and O atoms in the heterocycle is not more than 1. As used herein, the term xe2x80x9caromatic heterocyclic systemxe2x80x9d is intended to mean a stable 5- to 7-membered monocyclic or bicyclic or 7- to 10-membered bicyclic heterocyclic aromatic ring which consists of carbon atoms and from 1, 2, 3, or 4 heterotams independently selected from the group consisting of N, O and S. It is preferred that the total number of S and O atoms in the aromatic heterocycle is not more than 1.
Examples of heterocycles include, but are not limited to, 1H-indazole, 2-pyrrolidonyl, 2H,6H-1,5,2-dithiazinyl, 2H-pyrrolyl, 3H-indolyl, 4-piperidonyl, 4aH-carbazole, 4H-quinolizinyl, 6H-1,2,5-thiadiazinyl, acridinyl, azocinyl, benzimidazolyl, benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl, benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazalonyl, carbazolyl, 4aH-carbazolyl, xcex2-carbolinyl, chromanyl, chromenyl, cinnolinyl, decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl, dihydrofuro [2,3-b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, 1H-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl, isobenzofuranyl, isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl (benzimidazolyl), isothiazolyl, isoxazolyl, morpholinyl, naphthyridinyl, octahydroisoouinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl., oxazolyl, oxazolidinylperimidinyl, phenanthridinyl, phenanthrolinyl, phenarsazinyl, phenazinyl, phenothiazinyl, phenoxathiinyl, phenoxazinyl, phthalazinyl, piperazinyl, piperidinyl, pteridinyl, piperidonyl, 4-piperidonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidlnyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothiazole, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxalinyl, quinuclidinyl, carbolinyl, tetrahydrofuranyl, tetrahydroisoauinolinyl, tetrahydroquinolinyl, 6H-1,2,5-thiadiazinyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, thianthreniyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl, xanthenyl. Preferred heterocycles include, but are not limited to, pyridinyl, furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, indolyl, benzimldazolyl, 1H-indazolyl, oxazolidinyl, benzotriazolyl, benzisoxazolyl, oxindolyl, benzoxazolinyl, or isatinoyl. Also included are fused ring and spiro compounds containing, for example, the above heterocycles.
As used herein to describe the substituents R26 and R27, the term xe2x80x9cunsaturated carbocyclexe2x80x9d means a carbocycle that has at least one multiple bond, that one multiple bond being between the carbon atom attached to the divalent carbon radical specified in the formula of the stable hydrazone moiety and an adjacent carbon atom, examples of which include cyclopentene, cyclohexene, and 1,4-cyclohexadiene.
As used herein to describe the substituents R26 and R27, the term xe2x80x9cunsaturated heterocyclexe2x80x9d means a heterocycle that has at least one multiple bond, that one multiple bond being between the carbon atom attached to the divalent carbon radical specified in the formula of the stable hydrazone moiety and an adjacent carbon atom. An aromatic heterocycle is considered an unsaturated heterocycle.
As used herein, the term xe2x80x9calkarylxe2x80x9d means an aryl group bearing an alkyl group of 1-10 carbon atoms, such as toluenyl; the term xe2x80x9caralkylxe2x80x9d means an alkyl group of 1-10 carbon atoms bearing an aryl group, such as benzyl; the term xe2x80x9carylalkarylxe2x80x9d means an aryl group bearing an alkyl group of 1-10 carbon atoms bearing an aryl group, such as phenylmethylphenyl; and the term xe2x80x9cheterocycloalkylxe2x80x9d means an alkyl group of 1-10 carbon atoms bearing a heterocycle, such as pyridylmethyl or 2-imidazolylmethyl.
A xe2x80x9creducing agentxe2x80x9d is a compound that reacts with the radionuclide, which is typically obtained as a relatively unreactive, high oxidation state compound, to lower its oxidation state by transferring electron(s) to the radionuclide, thereby making it more reactive. Reducing agents useful in the preparation of radiopharmaceuticals and in diagnostic kits useful for the preparation of said radiopharmaceuticals include but are not limited to stannous chloride, stannous fluoride, formamidine sulfinic acid, ascorbic acid, cysteine, phosphines, and cuprous or ferrous salts. Other reducing agents are described in Brodack et. al., PCT Application 94/22496, which is incorporated herein by reference.
The term xe2x80x9cligandxe2x80x9d as used herein refers to a molecule or group of atoms that bonds to a metal ion through one of more of its constituent atoms, termed donor atoms.
The term xe2x80x9cdonor atomxe2x80x9d refers to the atom directly attached to a metal by a chemical bond.
The term xe2x80x9cligand precursorxe2x80x9d as used herein refers to a ligand in which one or more of its donor atoms bear a protecting group. A hydrazone is a precursor for a hydrazine ligand.
A xe2x80x9cdiagnostic kitxe2x80x9d or xe2x80x9ckitxe2x80x9d comprises a collection of components, termed the formulation, in one or more vials which are used by the practicing end user in a clinical or pharmacy setting to synthesize the radiopharmaceutical. The kit provides all the requisite components to synthesize and use the radiopharmaceutical except those that are commonly available to the practicing end user, such as water or saline for injection, a solution of the radionuclide, equipment for heating the kit during the synthesis of the radiopharmaceutical, if required, equipment necessary for administering the radiopharmaceutical to the patient such as syringes and shielding, and imaging equipment.
A xe2x80x9cbufferxe2x80x9d is a compound that is used to control the pH of the kit during its manufacture and during the synthesis of the radiopharmaceutical.
A xe2x80x9clyophilization aidxe2x80x9d is a component that has favorable physical properties for lyophilization, such as the glass transition temperature, and is added to the diagnostic kit to improve the physical properties of the combination of all the components of the kit for lyophilization.
A xe2x80x9cstabilization aidxe2x80x9d is a component that is added to the radiopharmaceutical or to the diagnostic kit either to stabilize the radiopharmaceutical once it is synthesized or to prolong the shelf-life of the kit before it must be used. Stabilization aids can be antioxidants, reducing agents or radical scavengers and can provide improved stability by reacting preferentially with species that degrade other components or the radiopharmaceutical.
A xe2x80x9csolubilization aidxe2x80x9d is a component that improves the solubility of one or more other components in the medium required for the synthesis of the radiopharmaceutical.
A xe2x80x9cbacteriostatxe2x80x9d is a component that inhibits the growth of bacteria in the diagnostic kit either during its storage before use of after the kit is used to synthesize the radiopharmaceutical.
The term xe2x80x9cpharmaceutically acceptablexe2x80x9d as used herein means that a component is sufficiently sterile, apyrogenic and of such a chemical and physical form to be safely administered to a mammal, preferably a human.
The radiopharmaceuticals of the present invention have the formula ML1L2L3, wherein M represents the transition metal radionuclide and L1, L2 and L3 represent three different ligands that are coordinated to the metal radionuclide. These complexes are thus comprised of a ternary ligand system with a 1:1:1 ligand stoichiometry. These complexes can be formed in high specific activity, have high stability in vitro, and their chemical and biological properties can be readily tailored to the desired radiopharmaceutical application by the selection of the ligands L1, L2 and L3.
The transition metal radionuclide is selected from the group: technetium-99m, rhenium-186 and rhenium-188. For diagnostic purposes Tc-99m is the preferred isotope. Its 6 hour half-life and 140 keV gamma ray emission energy are almost ideal for gamma scintigraphy using equipment and procedures well established for those skilled in the art. The rhenium isotopes also have gamma ray emission energies that are compatible with gamma scintigraphy, however, they also emit high energy beta particles that are more damaging to living tissues. These beta particle emissions can be utilized for therapeutic purposes, for example, cancer radiotherapy.
The coordination sphere of the radionuclide includes all the ligands or groups bound to the radionuclide. For a transition metal radionuclide to be stable it typically has a coordination number (number of donor atoms) comprised of an integer greater than or equal to 4 and less than or equal to 8; that is there are 4 to 8 atoms bound to the metal and it is said to have a complete coordination sphere. The requisite coordination number for a stable radionuclide complex is determined by the identity of the radionuclide, its oxidation state, and the type of donor atoms. If one ligand does not provide all of the atoms necessary to stabilize the metal radionuclide by completing its coordination sphere, the coordination sphere is completed by donor atoms from other ligands, termed co-ligands, which can also be either terminal or chelating.
The radiopharmaceuticals of the present invention are comprised of three ligands, L1, L2 and L3. The ligand L1 is a hydrazido or diazenido ligand having the formula xe2x95x90Nxe2x80x94NR1R2 or xe2x95x90N+xe2x95x90NR1 and results from the coordination of a hydrazine to the metal. A diazenido group can be either terminal (only one atom of the group is bound to the radionuclide) or chelating. In order to have a chelating diazenido group at least one other atom of the group must also be bound to the radionuclide. The ligand L2 is comprised of two or more hard donor atoms such as oxygen and amine nitrogen (sp3 hybridized). The donor atoms occupy at least two of the sites in the coordination sphere of the radionuclide metal. The ligand L3 is comprised of one to three soft donor atoms selected from the group: phosphine phosphorus, arsine arsenic, imine nitrogen (sp2 hybridized), sulfur (sp2 hybridized) and carbon (sp hybridized); atoms which have pi-acid character. Ligands L3 can be monodentate, bidentate or tridentate, the denticity is defined by the number of donor atoms in the ligand.
The chemical and physical properties of the radiopharmaceuticals of the present invention, such as their charge and lipophilicity, can be modified by the choice of substituents on the ligands, L1, L2 and L3. Substituents that increase the lipophilicity of the complexes are comprised of predominantly carbon-carbon bonds, for example, alkyl, aryl, alkenyl, alkynyl and cycloalkyl groups. Substituents that increase the hydrophilicity of the complexes are comprised predominantly of nitrogen or oxygen heteroatoms, for example, carboxyl, hydroxyl, sulfonate, phosphonate, as well as others. Substituents that effect the charge of the complexes are comprised of groups that are charged under physiological conditions, for example, carboxyl, sulfonate, phosphonate, and ammonium.
The lipophilicity and charge of radiopharmaceuticals determine to a large extent their biological properties, such as the organs in which they concentrate, the rate of clearance from the blood and the route of excretion from the body. For example, Deutsch et. al., U.S. Pat. No. 4,387,087 describes cationic, binary ligand complexes with a lipophilicity measured by the 1-octanol-water partition coefficient of  greater than 0.05 that are useful as hepatobiliary and myocardial imaging agents. Bergstein et. al., U.S. Pat. No. 5,279,811 describes a series of neutral and lipophilic complexes of technetium-99m useful as brain imaging agents. Also, the relationship between lipophilicity, as measured by HPLC retention time, and route of excretion has been described by Nunn in Nucl. Med. Biol., 1989, 16, 187-190, herein incorporated by reference in its entirety, for a series of Tc-99m labeled iminodiacetic acid derivatives. The ternary ligand complexes of the present invention provide three independent means for affecting their lipophilicity and charge by the choice of the substituents on the three ligands.
The ligands L1 in their uncoordinated or xe2x80x9cfree ligandxe2x80x9d state can be obtained for use in the synthesis of the radiopharmaceuticals of the present invention from commercial sources in the form of a hydrazine or hydrazine derivative or acid salt thereof. In addition, methods for synthesizing hydrazines and their derivatives are well known to those skilled in the art. A number of synthesis methods can be found in March, Advanced Organic Chemistry, 3rd edition, Wiley-Interscience, herein incorporated by reference. Preferred ligands L1 are hydrazines wherein the substituent R1 is aryl or heterocycle.
Protected hydrazines or hydrazine derivatives can also be synthesized in the form of a hydrazone. The hydrazone protecting group can be removed either prior to or concomitantly with the synthesis of the radiopharmaceuticals. Exemplary hydrazones include aldehyde or ketone hydrazones having substituents, designated R26 and R27 in this application, selected from hydrogen, alkyl, aryl and heterocycle, which can be conveniently synthesized by condensation of the aldehyde or ketone with the hydrazine. When one of the substituents R26 and R27 is selected from the group: nitrile, carboxylic acids, carboxylic acid esters, carboxamides, 1-alkenes, 1-alkynes, aryl, unsaturated heterocycle, and unsaturated carbocycle; or the two substituents R26 and R27 are taken together to form a ring system, the hydrazones have improved stability. The substituents in the group serve to stabilize the hydrazone by providing a conjugated pi-electron system either as a carbon-carbon double bond or an aromatic ring. Enhanced stability can also be provided by the chelate effect if the substituents are taken together in a ring system. The synthesis and use of hydrazine-derivatized biologically active molecules having these preferred hydrazones with enhanced stability as the protecting group for the hydrazines are described in co-pending U.S. Ser. No. 08/476,296, herein incorporated by reference.
The ligands, L2, in their uncoordinated or xe2x80x9cfree ligandxe2x80x9d state are functionalized aminoalcohols or aminocarboxylates having at least one amine nitrogen donor atom. At least one additional nitrogen or oxygen donor atom must be present in the ligand in substituents R7 through R13. A large number of ligands L2 can be obtained from commercial sources. Examples of ligands, L2, include the series of functionalized aminocarboxylates disclosed by Bridger et. al. in U.S. Pat. No. 5,350,837, herein incorporated by reference, that result in improved rates of formation of technetium labeled hydrazino modified proteins. We have determined that certain of these aminocarboxylates result in improved yields and higher specific activity of the radiopharmaceuticals of the present invention. The preferred ligands L2 are functionalized aminocarboxylates that are derivatives of glycine; the most preferred is tricine (tris(hydroxymethyl)methylglycine).
The ligands L3 that are comprised of phosphine or arsine donor atoms are trisubstituted phosphines, trisubstituted arsines, tetrasubstituted diphosphines and tetrasubstituted diarsines. The ligands L3 that are comprised of imine nitrogen are unsaturated or aromatic nitrogen-containing, 5 or 6-membered heterocycles. The ligands that are comprised of sulfur (sp2 hybridized) donor atoms are thiocarbonyls, comprised of the moiety Cxe2x95x90S. The ligands comprised of carbon (sp hybridized) donor atoms are isonitriles, comprised of the moiety CNR, where R is an organic radical. A large number of such ligands are available from commercial sources or can be synthesized by a variety of means known to those skilled in the art. A number of methods for synthesizing phosphines can be found in Kosolapoff and Maier, Organic Phosphorus Compounds: Wiley-Interscience: New York, 1972; Vol. 1. Isonitriles can be synthesized as described in European Patent 0107734 and in U.S. Pat. No. 4,988,827, herein incorporated by reference.
Preferred ligands L3 are trisubstituted phosphines and unsaturated or aromatic 5 or 6 membered heterocycles. References for the synthesis of specific preferred ligands can be obtained as follows: Tris(3-sulfonatophenyl)phosphine, sodium salt (TPPTS) was synthesized as described in Bartik et. al., Inorg. Chem., 1992, 31, 2667. Bis(3-sulfonatophenyl)phenylphosphine, sodium salt (TPPDS) and (3-sulfonatophenyl)diphenylphosphine, sodium salt (TPPMS) were synthesized as described in Kuntz, E., U.S. Pat. No. 4,248,802. We have disclosed in co-pending U.S. Ser. No. 08/415,908, and U.S. Ser. No. 60/013360 and 08/646,886, the disclosures of which are herein incorporated by reference in their entirety, that radiopharmaceuticals comprised of a biologically active molecule, Q, bearing a chelator or metal bonding unit and one or more ancillary or co-ligands L3 are more stable compared to radiopharmaceuticals that are not comprised of one or more ancillary ligands, L3; that is, they have a minimal number of isomeric forms, the relative ratios of which do not change significantly with time, and that remain substantially intact upon dilution. The radiopharmaceuticals of the present invention differ from those claimed in these co-pending applications by the absence of the biologically active group, Q, on ligand L1.
The radiopharmaceuticals of the present invention can be easily prepared by admixing a salt of a radionuclide, a ligand L1 as a hydrazine or hydrazone, a ligand L2, a ligand L3, and a reducing agent, in an aqueous solution at temperatures from 0 to 100xc2x0 C. When the ligand, L1, is a hydrazone, then it must first be converted to a hydrazine, which may or may not be protonated, prior to complexation with the metal radionuclide. The conversion of the hydrazone group to the hydrazine can occur either prior to reaction with the radionuclide or in the presence of the radionuclide In the latter case, the pH of the reaction mixture must be neutral or acidic.
Alternatively, the radiopharmaceuticals of the present invention can be prepared by first admixing a salt of a radionuclide, a ligand L2, and a reducing agent in an aqueous solution at temperatures from 0 to 100xc2x0 C. to form an intermediate radionuclide complex with the ligand L2 then adding the ligands L1 and L3 and reacting further at temperatures from 0 to 100xc2x0 C.
Alternatively, the radiopharmaceuticals of the present invention can be prepared by first admixing a salt of a radionuclide, a ligand L1 and a ligand L2, and a reducing agent in an aqueous solution at temperatures from 0 to 100xc2x0 C. to form an intermediate radionuclide complex, and then adding a ligand L3 and reacting further at temperatures from 0 to 100xc2x0 C.
The total time of preparation will vary depending on the identity of the radionuclide, the identities and amounts of the reactants and the procedure used for the preparation. The preparations may be complete, resulting in  greater than 80% yield of the radiopharmaceutical, in 1 minute or may require more time. If higher purity radiopharmaceuticals are needed or desired, the products can be purified by any of a number of techniques well known to those skilled in the art such as liquid chromatography, solid phase extraction, solvent extraction, dialysis or ultrafiltration.
The technetium and rhenium radionuclides are preferably in the chemical form of pertechnetate or perrhenate and a pharmaceutically acceptable cation. The pertechnetate salt form is preferably sodium pertechnetate such as obtained from commercial Tc-99m generators. The amount of pertechnetate used to prepare the radiopharmaceuticals of the present invention can range from 0.1 mCi to 1 Ci, or more preferably from 1 to 200 mCi.
The amount of the ligand L1 used to prepare the radiopharmaceuticals of the present invention can range from 0.01 xcexcg to 10 mg, or more preferably from 0.5 xcexcg to 200 xcexcg. The amount of the ligand L2 used can range from 0.1 mg to 1 g, or more preferably from 1 mg to 100 mg. The amounts of the ligand L3 used can range from 0.001 mg to 1 g, or more preferably from 0.01 mg to 10 mg. The amount used will be dictated by the amounts of the other reactants and the identity of the radiopharmaceuticals of the present invention to be prepared.
Suitable reducing agents for the synthesis of the radiopharmaceuticals of the present invention include stannous salts, dithionite or bisulfite salts, borohydride salts, and formamidinesulfinic acid, wherein the salts are of any pharmaceutically acceptable form. The preferred reducing agent is a stannous salt. The amount of a reducing agent used can range from 0.001 mg to 10 mg, or more preferably from 0.005 mg to 1 mg. The use of a reducing agent can be omitted if the ligand L3 can serve as both a reducing agent and a ligand. Ligands, L3, that can serve both functions are those comprised of phosphorus or arsenic donor atoms.
Another aspect of the present invention are diagnostic kits for the preparation of the radiopharmaceuticals useful as imaging agents. Diagnostic kits of the present invention comprise one or more vials containing the sterile, nonpyrogenic, formulation comprised of a predetermined amount of the ligands L1, L2 and L3 and optionally other components such as reducing agents, buffers, lyophilization aids, stabilization aids, solubilization aids and bacteriostats. The inclusion of one or more optional components in the formulation will frequently improve the ease of synthesis of the radiopharmaceutical by the practicing end user, the ease of manufacturing the kit, the shelf-life of the kit, or the stability and shelf-life of the radiopharmaceutical. The one or more vials that contain all or part of the formulation can independently be in the form of a sterile solution or a lyophilized solid.
Buffers useful in the preparation of radiopharmaceuticals and in diagnostic kits useful for the preparation of said radiopharmaceuticals include but are not limited to phosphate, citrate, sulfosalicylate, and acetate. A more complete list can be found in the United States Pharmacopoeia.
Lyophilization aids useful in the preparation of diagnostic kits useful for the preparation of radiopharmaceuticals include but are not limited to mannitol, lactose, sorbitol, dextran, Ficoll, and polyvinylpyrrolidine(PVP).
Stabilization aids useful in the preparation of radiopharmaceuticals and in diagnostic kits useful for the preparation of said radiopharmaceuticals include but are not limited to ascorbic acid, cysteine, monothioglycerol, sodium bisulfite, sodium metabisulfite, gentisic acid, and inositol.
Solubilization aids useful in the preparation of radiopharmaceuticals and in diagnostic kits useful for the preparation of said radiopharmaceuticals include but are not limited to ethanol, glycerin, polyethylene glycol, propylene glycol, polyoxyethylene sorbitan monooleate, sorbitan monooleate, polysorbates, poly(oxyethylene)poly(oxypropylene)poly(oxyethylene) block copolymers (Pluronics) and lecithin. Preferred solubilizing aids are polyethylene glycol, and Pluronics.
Bacteriostats useful in the preparation of radiopharmaceuticals and in diagnostic kits useful for the preparation of said radiopharmaceuticals include but are not limited to benzyl alcohol, benzalkonium chloride, chlorbutanol, and methyl, propyl or butyl paraben.
The amounts of each component in the formulation are determined by a variety of considerations that are in some cases specific for that component and in other cases dependent on the amount of another component or the presence and amount of an optional component. In general, the minimal amount of each component is used that will give the desired effect of the formulation. The desired effect of the formulation is that the practicing end user can synthesize the radiopharmaceutical and have a high degree of certainty that the radiopharmaceutical can be safely injected into a patient and will provide diagnostic information about the disease state of that patient.
The radiopharmaceuticals are administered by intravenous injection, usually in saline solution, at a dose of 1 to 100 mCi per 70 kg body weight, or preferably at a dose of 5 to 50 mCi. Imaging is performed using known procedures. Detailed procedures for imaging various organs in the body, including the heart, brain, lungs, liver and kidneys, and diagnosing diseases affecting those organs from the images can be found in Early and Sodee, Principles and Practice of Nuclear Medicine, 2nd edition, Mosby-Year Book, Inc., 1995, herein incorporated by reference.